The present invention relates to a double joint for connecting three elements of a foldable structure, two of the elements being capable of pivoting in an identical plane and being locatable at a desired angle in relation to the third.
Double joints are utilised for connecting together three elements of a foldable assembly, such as a camping table or an infant's cot and should preferably exhibit the following characteristics. Firstly, in the position of use, one of the elements should be locked in position in a relatively simple manner, relative to the other two elements. Secondly, the three elements must remain in the same plane (irrespective of whether they are in their locked position or not). Thirdly, the joint must be relatively resistant to forces which are applied perpendicularly to the plane containing the elements. Fourthly, the thickness of the joint should be approximately the same as the thickness of the other elements of the foldable structure, and finally, it should be almost impossible for a user to trap his fingers when closing the joint.
A double joint is known in which locking of the joint is possible. In such a joint a first element has a nose portion integral therewith. In a particular position of the joint, this nose portion engages in a groove formed in a part which is formed integrally with a second element of the joint. The first and second elements pivoting relative to a member which is connected to a third element of the joint. However, in such an arrangement, the joint can only be unlocked in one position. Additionally the nose portion generally has sharp edges which can injure the user.